What are chlorates?
Chlorates are chemical compounds primarily formed from chlorine used in the process of disinfecting drinking water. During this disinfection process, chlorates can form as undesirable by-products.
What are the standards for chlorates in distribution water?
European Directive 2020/184 on the quality of water intended for human consumption defines a standard for chlorates that can range between 0.25 and 0.70 mg/l (milligrams per liter). In Wallonia, this standard has been set at 0.25 mg/l. Water distributors have until January 12, 2026, to comply with this new limit.
Are there chlorates in tap water?
Yes, there can be chlorates in tap water, but generally in very low concentrations. Chlorates are by-products that form when chlorine is used to disinfect drinking water. Chlorine is commonly used in water treatment to kill bacteria and other pathogens. However, when chlorine breaks down, chlorates can form.
Is the presence of chlorates in tap water monitored?
Yes, distributors have been required to monitor the presence of chlorates in tap water since January 2024. The SWDE (Walloon Water Management) conducts regular analyses to monitor and adjust water treatments as necessary to comply with the future standard of 0.25 mg/l (milligrams per liter) of chlorates.
How are chlorates detected in distribution water?
Laboratories responsible for water quality control in Wallonia use ion chromatography to analyze chlorates in water. This technique separates the different ions present in the water sample and then measures them separately, including chlorates. This method is highly sensitive and allows the detection of chlorates at concentrations well below regulatory limits.
What solutions are implemented in case of chlorates presence?
Managing chlorate levels in distribution water mainly relies on the level of chlorination of the water and the quality of the reagent used:
Reduce water chlorination without compromising its disinfection effectiveness.
Use high-quality chlorination products. The quality of chlorine degrades over time, leading to the formation of chlorates. This degradation is accelerated by temperature and exposure to light.